The Robert H. Lurie Comprehensive Cancer Center Flow Cytometry Core Facility provides comprehensive flow cytometry and cell sorting services. The Flow Cytometry Core Facility serves investigators of the Cancer Center, Northwestern University Medical School, Northwestern University and other affiliated institutions by providing access to routine flow cytometry assays such as immunophenotyping and DNA analysis. However, research users encompass individuals with a broad spectrum of training in the basic and clinical sciences, and thus, a major goal of the facility is to provide the guidance, technical assistance, and equipment for investigators to utilize more complex multi-parametric, multi-laser measurements as well as cell sorting in their research regardless of their level of cytometry expertise. Services provided by the facility personnel extend from consultation on experimental design, sample preparation and data analysis to instrument operation and set-up for cell-sorting and multi-laser operation. In addition, the Core Facility has an active program of assay development guided by the interests of the investigators. As such, the Flow Cytometry Core Facility serves as a focus for individuals interested in cellular based measurements and cellular heterogeneity in disease providing critical support for cancer related research within the institution. The equipment and expertise housed within the Core Facility permits implementation of most flow cytometry assays that have been published. The facility includes both a bench top single laser instrument (Beckman Coulter XL) and a four laser research sorting instrument (Beckman Coulter ELITE ESP) as well as off-line data analysis hardware and software. The Core Facility is now heavily utilized by a wide number of investigators (>50) over 64% of which are full Cancer Center members with peer reviewed funding.